id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
2537	"Host not found in resolver ""kube-dns.kube-system.svc.cluster.local"". Apparently 'resolver' does not work with long DNS names"	yersan@…		"Hi, I have the following simple configuration:


{{{
/ # cat /etc/nginx/conf.d/nginx.conf
server {
    listen 8080;
    server_name $hostname;
    location / {
        root /usr/share/nginx/html;
        index index.html;
        try_files $uri $uri/ /index.html;
    }
    location /api/ {
        error_log  /var/log/nginx/api-error.log debug;
        resolver kube-dns.kube-system.svc.cluster.local valid=10s;
        set $target todo-list-backend-svc.default.svc.cluster.local;
        proxy_pass http://$target;
    }
}}}

Which gives me the following error:


{{{
/ # nginx -s reload
2023/08/26 11:16:25 [emerg] 60#60: host not found in resolver ""kube-dns.kube-system.svc.cluster.local"" in /etc/nginx/conf.d/nginx.conf:11
nginx: [emerg] host not found in resolver ""kube-dns.kube-system.svc.cluster.local"" in /etc/nginx/conf.d/nginx.conf:11
}}}

I've checked that ""kube-dns.kube-system.svc.cluster.local"" can be resolved locally:


{{{
/ # nslookup kube-dns.kube-system.svc.cluster.local
Server:		10.96.0.10
Address:	10.96.0.10:53


Name:	kube-dns.kube-system.svc.cluster.local
Address: 10.96.0.10
}}}

This is my /etc/resolv.conf:

{{{

/ # cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local localdomain
options ndots:5
}}}

When I remove the ""svc.cluster.local"" from the DNS name, nginx is reloaded without any issue:


{{{
/ # cat /etc/nginx/conf.d/nginx.conf
server {
    listen 8080;
    server_name $hostname;
    location / {
        root /usr/share/nginx/html;
        index index.html;
        try_files $uri $uri/ /index.html;
    }
    location /api/ {
        error_log  /var/log/nginx/api-error.log debug;
        resolver kube-dns.kube-system valid=30s;
        set $target todo-list-backend-svc.default.svc.cluster.local;
        proxy_pass http://$target;
    }
/ # nginx -s reload
2023/08/26 11:20:03 [notice] 67#67: signal process started
/ #
}}}

So, what is going wrong here? It looks like resolver is unable to deal with long DNS names.





"	defect	closed	major		nginx-module	1.25.x	invalid	ngx_http_core_module		Linux todo-list-front-5b4c5887fd-tc2b4 5.14.0-162.22.2.el9_1.x86_64 #1 SMP PREEMPT_DYNAMIC Wed Mar 15 14:44:24 EDT 2023 x86_64 Linux	"nginx version: nginx/1.24.0
built by gcc 12.2.1 20220924 (Alpine 12.2.1_git20220924-r4)
built with OpenSSL 3.0.7 1 Nov 2022 (running with OpenSSL 3.0.10 1 Aug 2023)
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --with-perl_modules_path=/usr/lib/perl5/vendor_perl --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-Os -fomit-frame-pointer -g' --with-ld-opt=-Wl,--as-needed,-O1,--sort-common"